If you've ever been given a local anaesthetic, you'll know about the effects – and the side effects – of these drugs. For example, dentists usually inject lidocaine into the gum before filling a cavity or pulling a tooth out, to numb the jaw quadrant on which the procedure is being performed. Although temporary, the anaesthetic can take a few hours to wear off, leaving you unable to eat, drink or talk properly after leaving the surgery. You may even experience blurred vision, or have difficulty blinking, if the anaesthetic inadvertently affects other parts of your face.

A newly-developed molecule could overcome these problems. It can be activated by light to silence pain-sensing neurons and then inactivated, also by light, within fractions of a second. The molecule, described by American and European researchers in the journal Nature Methods, could prove to be a powerful new research tool and, although still in the experimental stage, may eventually be used in the clinic as a selective and rapidly reversible painkiller.


http://www.guardian.co.uk/science/ne.../2012/feb/21/1